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DIY Fitting

Installing a cat flap is a job probably best left to a professional. However, if you’re a competent DIY-er and keen to have a go, here are my top tips. 
Secure petWALK large pet door installed in wall
petWALK medium in panelled wooden door
cat flap tucked securely in corner of wooden door
Manual cat flap located away from door latch
• Security: Consider seriously whether the presence of a pet door might compromise your home security. 
When deciding where to install a cat flap, bear in mind whether a burglar would be able to reach through the flap and access the door latch or key. Never leave the door keys in the lock overnight. 
Burglars could climb through dog doors so take special care to secure any internal security panel at night or when going out. Pet friendly movement detectors (PIR) are available if you have a home alarm system fitted.
petWALK pet doors have a built in alarm system and can also be connected to your existing house alarm. These doors are at least as secure as high quality house doors.


• Wooden door. It is generally quite straightforward to fit a cat flap within a flat panel of a wooden door. A suitably sized hole is cut with a jigsaw or reciprocating saw.
A door with narrow panels will require careful attention to avoid weakening the structure of the door.
 
With wooden doors, it is particularly important to make the installation weathertight - rain penetrating into the door will in time result in the wood rotting. I always form a weathertight seal between the cat flap and the outside surface of the the door using a long life weatherproof sealant.
The burglar proof, airtight and fully insulated petWALK medium pet door.
SureFlap in oak front door
SureFlap fitted into oak front door
Brown SureFlap cat flap in panelled hardwood front door
SureFlap fitted to panelled hardwood front door
SureFlap fitted into wooden door
SureFlap in front door behind security grill
SureFlap fitted to hardwood door and opening clear of external security gate
Cat flap in flat door panel
SureFlap fitted into wooden door relieving cat's need to scratch at the door!
Manual 4-way cat flap opening clear of external security grill
DogWalk Small Dog Door W-SDDT in panelled wooden door. This model boasts a four way lock.
SureFlap fitted to door panel
PetPorte microchip cat flap fitted to panelled wooden back door
4-way cat flap fitted to panelled wooden front door
Sureflap sits snugly within a panel
PetMate medium dog door in panelled wooden door
PetMate Medium Dog Door 215 fitted into panelled wooden door
Cat flap in wooden side panel
SureFlap tucked away discretely in side panel
SureFlap in wooden front door

SureFlap in laminated glass sash window
SureFlap fitted into new laminated glass sash window
SureFlap fitted into new laminated glass pane and access step fitted to wooden door frame below
Staywell Deluxe manual cat flap in laminated glass window
Broken glass in sash window replaced with laminated glass and Staywell manual 4-way locking cat flap re-fitted
Manual CatMate cat flap in Georgian glazed wooden door
Manual cat flap fitted through pane of glazed door with Georgian glazing bars
CatMate Cat flap fitted in narrow side window
Cat Mate 4-way locking cat flap fitted into narrow glazed side light
SureFlap fitted into new laminated glass in narrow side light
SureFlap fitted into sash window
SureFlap fitted in laminated glass door and rotten beading replaced
Wired glass replaced by polycarbonate sheeting and SureFlap fitted
PetMate medium dog door in solid polycarbonate window
PetMate Medium Dog Door 215 mounted in solid polycarbonate sheet in wooden framed door
SureFSureFlap fitted in double glazed uPVC door
SureFlap fitted in Crittall steel window
Steel 'Crittall' window re-glazed in solid polycarbonate to accommodate a SureFlap
• Single glazed window or door. Older doors and windows in particular may contain glass which has not been toughened by a special heat treatment to make it safe. This should be replaced by a new pane of laminated or toughened safety glass in which a circular hole has been pre-cut by a glazier. Toughened glass is indicated by an etched symbol in the corner of the pane.
Sometimes the glass is too narrow to accommodate the circular hole required for a cat flap. In this case a pane of solid polycarbonate may be used to advantage as a tighter rectangular hole can be cut in this. Polycarbonate is a security product - it is virtually indestructible.  However, it is more flexible and softer than glass and more likely to get scratched over time.

• Double glazed window or door. Double glazed doors and windows usually contain safety glass which has been toughened by a special heat treatment. Any attempt to cut a hole in this will cause it to fracture into myriad tiny pieces. In any case, it would not be possible to re-seal a unit after cutting a hole in it. So if you have a double-glazed window or door you will need to get a replacement unit manufactured with a circular hole pre-cut for the cat flap. A replacement full size double glazed door unit costs from about £160 to £240 or so depending on its size and specification. 
If the glazing is very narrow a cat flap may need to be accommodated in a rectangular rather than a circular hole. A rectangular hole can be cut through glass using a high pressure abrasive waterjet. However, this adds considerably to the cost of the unit. Larger dog doors will also require a rectangular hole.
It is important to properly "toe and heel" the glazed unit in doors and opening windows. This is the process by which the door is diagonally braced by the glazing in order to maintain the door's geometry. Failure to do this properly leads to the door or window "dropping", and the locks or latches not closing easily.
PetWalk medium in aluminium bi-fold doors
The petWALK medium pet door - the draught and burglar proof solution
SureFlap in double glazed door with Georgian glazing bars
SureFlap cat flap in narrow double glazed window
SureFlap fitted in narrow conservatory window
SureFlap Pet Door fitted in aluminium framed window
SureFlap Pet Door fitted in Pilkington Textured Glass Florielleâ„¢
SureFlap Pet Door in double glazed wooden Bi-fold doors
Dogwalk dog flap in double glazed uPVC door
Dogwalk Dog Door G-DD in white
Dog door in leaded glass door
Dogwalk Dog Door G-DD (clear) fitted in leaded glazing in aluminium door
Dog door in glass door
Dogwalk Dog Door G-DD in clear
Cat Mate cat flap 210 fitted in Pilkington textured glass Contoraâ„¢
Medium dog flap in double glazed door
Staywell Aluminium Medium Dog Door #620
Rectangular hole cut in glass for Staywell aluminium medium dog door
Staywell Aluminium Medium Dog Door #620
Medium dog flap in glazed uPVC patio door
Staywell Aluminium Medium Dog Door #620
Cat flap in leaded double glazed door
SureFlap in double glazed leaded door
The CatMate 360W features a larger than average flap opening
Cat flap in diamond leaded door
SureFlap in diamond leaded double glazed uPVC door

SmartDoor Electronic Pet Door (Large)
SmartDoor Electronic Pet Door (Large) with Collar Key and multi-point locking system
Dog Mate medium dog door 215 in uPVC door panel
Dog Mate medium dog door 215 fitted into flat uPVC door panel
SureFlap fitted into flat uPVC door panel
Staywell large cat/small dog flap in uPVC door panel
Staywell Large Cat/Small Dog Flap #280EF
SureFlap fitted neatly into decorative uPVC front door
Large Cat Flap CatMate 221 in composite door
SureFlap DualScan in uPVC door panel
SureFlap Dualscan fitted into panelled uPVC door
SureFlap fitted to narrow uPVC side panel
SureFlap fitted below decorative beading on uPVC panel
SureFlap in a decorative panelled uPVC door
SureFlap in decorative uPVC panel
Staywell large aluminium dog door 640 in uPVC panel in place of double glazing
Double glazed window has been replaced by a uPVC panel into which a Staywell large aluminium dog door 640ML has been fitted
Cat flap in composite door
SureFlap in composite door
• uPVC, GRP and composite door or panel. The construction of these varies greatly. Some comprise a very flimsy plastic outer skin bonded to a soft insulating polystyrene core. Great care should be exercised in cutting through these as they are fragile - especially in cold weather when they become quite brittle! Some uPVC door panels incorporate a sheet of ply or mdf for added strength while better quality doors incorporate a sheet of aluminium or steel for security. Bear in mind that any metal within a door may interfere with the functioning of a microchip cat flap. All these can still be cut with a standard electric jig saw fitted with a fine toothed blade. 
Additional complexity occurs where the panel incorporates raised decorative features such as panelling. Not only must the raised feature be cut away intricately to accommodate the pet flap neatly, but the outside face must be rendered rainproof where the raised feature has been cut back.

• Metal faced door.  These doors offer greater security than the ubiquitous uPVC door. The metal may be aluminium or steel, steel being stronger than aluminium. They are treated like uPVC doors but may be tougher to cut through. Bear in mind that any metal within a door may interfere with the functioning of a microchip cat flap. Sometimes an oversize hole will have to be cut to avoid such interference. In this case it will be necessary to fill in the oversize gap and render it rainproof.
Take care when cutting steel as the cut edges may be dangerously sharp. I file these edges smooth so that someone removing the pet door at a later date won't be so likely to hurt themselves.
SureFlap fitted through aluminium faced door panel
SureFlap in steel reinforced door
SureFlap fitted through thick steel security plate bolted to wooden door
Hole cut through aluminium faced composite door ready to receive SureFlap
SureFlap fitted through aluminium faced composite door
Pet Mate Small Dog Door 221 fitted into aluminium face door panel
Hole cut out of aluminium faced door ready to receive SureFlap
Oversize hole cut out of steel faced door panel to avoid interference with SureFlap microchip reader
Cut out in aluminium reinforced uPVC door panel
SureFlap in steel faced door panel
SureFlap in triple steel reinforced panel
PetPorte SmartDoor installed in steel garage door
PetPorte fitted to steel up-and-over garage door

The petWALK large pet door is burglar proof, airtight and fully insulated
SureFlap fitted to a pebbledashed wall
PetPorte microchip cat flap fitted through cavity wall
SureFlap fitted through solid brick wall
SureFlap fitted through extra thick 420mm (16") solid wall and tunnel lined in cement render
SureFlap located discretely in corner of room
SureFlap Pet Door through wall
SureFlap Pet Door positioned as low as possible for Dachshund Jack
Manual 4-way locking cat flap in brick wall
4-way locking cat flap in cavity wall
PetMate Electromagnetic dog door 259 through cavity wall for French Bulldog Kiera
Cutting hole through cavity wall brickwork
Cutting a hole through a tiled brick wall for a large dog door
SureFlap tucked into corner of solid brick wall
SureFlap DualScan installed in cavity wall using a diamond core drill
Tunnel for SureFlap cut with diamond core drill. This is a timber framed house clad in brick.
Hole for SureFlap cut through 430mm (17") thick brick wall using a diamond core drill
Hole for SureFlap cut through cavity wall with diamond core drill
Hole for SureFlap cut through solid brick wall with diamond core drill
Tunnel for manual cat flap cut through tile hung wall with diamond core drill.
SureFlap on inside face, Staywell Classic cat flap on outside face
• Brick wall. A rectangular hole can be cut through a solid or cavity wall. With timber framed homes take care to locate the structural timbers before cutting into the wall - these must not be cut!
Check that there are no electric cables, gas, water or waste pipes where you are going to cut into the wall. A cable detector is helpful but has limited depth range. Avoid cutting a hole very close to a door or window as this could weaken the wall. A series of holes drilled through the wall with a masonry drill facilitates chopping out the hole using a cold chisel and club hammer. Be very very careful if using a mechanical breaker as you risk cracking the surrounding brickwork and mortar joints! For large dog doors I recommend providing some support to the brickwork above the hole. I use galvanised steel bars to span the opening.
Take care not to bridge any damp proof course as this may introduce dampness into the wall.
Cut the tunnel with a slight slope to the garden so that it can shed any rain that might be blown into it.
The hole can be lined with a plastic tunnel - this will span the space in a cavity wall.
The cat flap is almost always fixed to the interior surface of the wall. On the outside face of the wall, fill the gap between the cat flap tunnel and the surrounding wall to prevent rain getting into the wall.
To reduce draughts and heat loss consider fitting a second free-swinging cat flap to the exterior face of the wall.

• Weatherproofing. Take care to seal between the cat flap or tunnel liner and the outside face of the wall, door or window in order to keep rainwater out -  see the accompanying pictures. Use a suitable flexible sealant such as building silicone or frame sealant, although I prefer to use one of the superior MS polymer sealants. 
How to seal cat flap to uPVC
Sealant applied to SureFlap Pet Door in a uPVC door panel
How to seal SureFlap glass mounting adaptor
Sealant applied to SureFlap in glazing
How to seal cat flap in wall
Sealant applied to SureFlap in a brick wall
Sealant applied to SureFlap in a rendered wall

Walkway and ramp allow Cassius to reach his first floor SureFlap
Ramp cat access to first floor window
Window ledge extended adjacent to SureFlap
Cat ladder to first floor window
Cat ladder to first floor window (Not my work)
uPVC step for cat access
Access step fitted to wooden patio door
Ramp access to petWALK large through wall
Access ramp for labrador Maggie. I used pressure treated timber and stainless steel fixings throughout.
Access step fitted to wooden front door
Cat access ledge
This SureFlap is located high up in the door tobe accessible from the flight of stairs inside. A shelf was give the cat access from outside.
Windowsill shelf for cat access
Shelf fitted to windowsill
Access steps fitted to both inside and outside of uPVC framed door
Plastic cat steps to window
Proprietary cat steps
Access ramp to cat flap (not my work)
Brick steps for cat access
Brick staircase access to SureFlap (Not my work)
Log pile steps access to SureFlap (not my work)
Plastic cat steps
Plastic steps to access cat flap in glazed door
• Accessibility. Sometimes the only place a pet door can be fitted is a window too far above the ground for the cat or dog to reach easily. In such cases a step, stairs, ramp or even a ladder can be provided to help the animal access the pet door. 
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